1 // Concept-constrained comparison implementations -*- C++ -*-
2
3 // Copyright (C) 2019-2023 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 /** @file bits/ranges_cmp.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{functional}
28 */
29
30 #ifndef _RANGES_CMP_H
31 #define _RANGES_CMP_H 1
32
33 #if __cplusplus > 201703L
34 # include <bits/move.h>
35 # include <concepts>
36
37 namespace std _GLIBCXX_VISIBILITY(default)
38 {
39 _GLIBCXX_BEGIN_NAMESPACE_VERSION
40
41 struct __is_transparent; // not defined
42
43 // Define std::identity here so that <iterator> and <ranges>
44 // don't need to include <bits/stl_function.h> to get it.
45
46 /// [func.identity] The identity function.
47 struct identity
48 {
49 template<typename _Tp>
50 [[nodiscard]]
51 constexpr _Tp&&
52 operator()(_Tp&& __t) const noexcept
53 { return std::forward<_Tp>(__t); }
54
55 using is_transparent = __is_transparent;
56 };
57
58 #ifdef __cpp_lib_concepts
59 // Define this here, included by all the headers that need to define it.
60 #if __cplusplus > 202002L
61 #define __cpp_lib_ranges 202202L
62 #else
63 #define __cpp_lib_ranges 202110L
64 #endif
65
66 namespace ranges
67 {
68 namespace __detail
69 {
70 // BUILTIN-PTR-CMP(T, <, U)
71 // This determines whether t < u results in a call to a built-in operator<
72 // comparing pointers. It doesn't work for function pointers (PR 93628).
73 template<typename _Tp, typename _Up>
74 concept __less_builtin_ptr_cmp
75 = requires (_Tp&& __t, _Up&& __u) { { __t < __u } -> same_as<bool>; }
76 && convertible_to<_Tp, const volatile void*>
77 && convertible_to<_Up, const volatile void*>
78 && (! requires(_Tp&& __t, _Up&& __u)
79 { operator<(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
80 && ! requires(_Tp&& __t, _Up&& __u)
81 { std::forward<_Tp>(__t).operator<(std::forward<_Up>(__u)); });
82 } // namespace __detail
83
84 // [range.cmp] Concept-constrained comparisons
85
86 // _GLIBCXX_RESOLVE_LIB_DEFECTS
87 // 3530 BUILTIN-PTR-MEOW should not opt the type out of syntactic checks
88
89 /// ranges::equal_to function object type.
90 struct equal_to
91 {
92 template<typename _Tp, typename _Up>
93 requires equality_comparable_with<_Tp, _Up>
94 constexpr bool
95 operator()(_Tp&& __t, _Up&& __u) const
96 noexcept(noexcept(std::declval<_Tp>() == std::declval<_Up>()))
97 { return std::forward<_Tp>(__t) == std::forward<_Up>(__u); }
98
99 using is_transparent = __is_transparent;
100 };
101
102 /// ranges::not_equal_to function object type.
103 struct not_equal_to
104 {
105 template<typename _Tp, typename _Up>
106 requires equality_comparable_with<_Tp, _Up>
107 constexpr bool
108 operator()(_Tp&& __t, _Up&& __u) const
109 noexcept(noexcept(std::declval<_Up>() == std::declval<_Tp>()))
110 { return !equal_to{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
111
112 using is_transparent = __is_transparent;
113 };
114
115 /// ranges::less function object type.
116 struct less
117 {
118 template<typename _Tp, typename _Up>
119 requires totally_ordered_with<_Tp, _Up>
120 constexpr bool
121 operator()(_Tp&& __t, _Up&& __u) const
122 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
123 {
124 if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>)
125 {
126 if (std::__is_constant_evaluated())
127 return __t < __u;
128
129 auto __x = reinterpret_cast<__UINTPTR_TYPE__>(
130 static_cast<const volatile void*>(std::forward<_Tp>(__t)));
131 auto __y = reinterpret_cast<__UINTPTR_TYPE__>(
132 static_cast<const volatile void*>(std::forward<_Up>(__u)));
133 return __x < __y;
134 }
135 else
136 return std::forward<_Tp>(__t) < std::forward<_Up>(__u);
137 }
138
139 using is_transparent = __is_transparent;
140 };
141
142 /// ranges::greater function object type.
143 struct greater
144 {
145 template<typename _Tp, typename _Up>
146 requires totally_ordered_with<_Tp, _Up>
147 constexpr bool
148 operator()(_Tp&& __t, _Up&& __u) const
149 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
150 { return less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
151
152 using is_transparent = __is_transparent;
153 };
154
155 /// ranges::greater_equal function object type.
156 struct greater_equal
157 {
158 template<typename _Tp, typename _Up>
159 requires totally_ordered_with<_Tp, _Up>
160 constexpr bool
161 operator()(_Tp&& __t, _Up&& __u) const
162 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>()))
163 { return !less{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); }
164
165 using is_transparent = __is_transparent;
166 };
167
168 /// ranges::less_equal function object type.
169 struct less_equal
170 {
171 template<typename _Tp, typename _Up>
172 requires totally_ordered_with<_Tp, _Up>
173 constexpr bool
174 operator()(_Tp&& __t, _Up&& __u) const
175 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>()))
176 { return !less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); }
177
178 using is_transparent = __is_transparent;
179 };
180
181 } // namespace ranges
182 #endif // library concepts
183 _GLIBCXX_END_NAMESPACE_VERSION
184 } // namespace std
185 #endif // C++20
186 #endif // _RANGES_CMP_H